KR940011879B1 - Grounding arrangement useful in a display apparatus - Google Patents

Abstract

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Description

Grounding device for display device

1 is a partial block diagram of the present invention and a partial schematic view of a television receiver embodying a preferred embodiment.

Figure 1 (a) is a schematic view of a modification of the preferred embodiment of the present invention shown in Figure 1;

* Explanation of symbols for main parts of the drawings

1: tuner 5: detector

7: video processing unit 11: deflection processing unit

15: audio processing unit 21: control unit

25 microprocessor 27 tuner control unit

29: receiver control unit

The present invention relates to a grounding device which is particularly useful in display systems such as television receivers, monitors or similar devices.

Modern display systems such as television receivers and monitors provide a number of user characteristics that require a control unit that is connected to almost all main signal processing devices such as tuners, video, audio and deflection units. In such a device, the surroundings are arranged around an extensive reference potential or ground path in order to prevent unwanted currents and voltages from operating in the display system from being generated in the reference potential or ground path due to the operation of the signal processing device. Should be

In one aspect of the invention, a magnetic field generated by a deflection unit of a display system generates a large current in a closed loop reference potential or ground path that can cause disturbance of the reference potential for signals propagated in various parts of the display system. It's about recognizing what you can induce.

In a preferred embodiment of the present invention, a control system having first and second interconnection units for controlling the difference signal processing portion of a device such as a television receiver or a monitor is magnetically capable of being generated by a deflection unit. First and second unconnected reference potential input points are provided for receiving the reference potential from another point on the reference potential (ie ground) bus to construct a reference potential disturbance device without a continuous closed loop dependent on the induced current. . The threshold response gate is selectively connected when the potential difference between the first and second control units exceeds a threshold to prevent an excessively large and possibly destructive potential difference from occurring due to, for example, the high voltage discharge of the associated display tube. Or is coupled between the reference potential input points of the first and second control units for clamping together.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In the figure, the multiconductor signal path is represented by a double line.

The television receiver shown in FIG. 1 includes a tuner 1 for tuning the RF television signal corresponding to the channel selected to form the corresponding IF signal. The IF signal is filtered by the IF filter 3 and detected by the detector 5 to generate baseband composite video and audio signals. The composite video signal is a video processing unit 7 for processing the luminance and chromatic components of the video signal to generate red (R), green (G) and blue (B) driving signals for each electron gun of the image group 9. ) Is combined. The video signal is also coupled to the deflection processing unit 11, which is coupled to a deflection coil 13 associated with the image tube 9 for deflecting the electron beam generated by the electron gun of the image tube 9. The synchronization component of the video signal is processed to generate H) and vertical (V) deflection signals. The voltage for operating the water receiver including the high voltage HV for the image tube 9 is also generated by the deflection processing unit 11. The audio signal generated by the detector 5 is coupled to an audio processing unit 15 which supplies left (L) and right (R) stereo signals to the speakers 17 and 19.

The various functions of the receiver performed by the processing unit as described above are in communication with the control unit 21 by the microprocessor 25 and in response to a user command supplied by the means of the user input unit 23. 21). The user input unit 23 may be provided with a keyboard mounted on the receiver itself or on a remote control transmitter coupled to the receiver via an infrared or ultrasonic link. Commands from the user input unit 23 take the form of digitally encoded signals and the microprocessor 25 decodes these encoded signals and generates a real control signal for controlling several processing units. Generate a more digitally encoded signal for 21.

The control unit 21 is incorporated into a single integrated circuit (denoted by dashed lines), for example using CMOS technology, which is the first control unit 27 and the video processing unit 7 for controlling the tuner 1, It is divided into a second control unit 29 for controlling another processing unit of the receiver including the deflection processing unit 11 and the audio processing unit 15. The reason for the division will be described below. The microprocessor 25 is provided with a first or tuner control unit 27 and a conductor via a data bus 31 and conductors connected to respective terminals of the control unit 21 (generally denoted by a rectangle 33). It is coupled to the second or receiver control unit 29. The tuner control unit 27 and the receiver control unit 29 are electrically interconnected by the data bus 31.

The tuner control unit 27 generates a tune control signal and a band switching signal to the tuner 1 to tune a selected one of a plurality of RF television signals received corresponding to each channel. The tuner control unit 27 is coupled to the tuner 1 via a conductor connected to the control bus 35 and each terminal of the control unit 21 (generally denoted by the rectangle 37). Tuner control unit 27, for example, on September 20, 1983. Tultz and M. blood. It may be equipped with a phase locked loop or frequency synthesizer described in US Pat. No. 4,405,947 issued under the name of French. The phase locked loop receives a frequency-divided variation of the local oscillator signal generated within the tuner (and the control bus 35 between the tuner control unit and tuner 1 with arrows at both ends), which is called a frequency error pulse, The amplitude and duration of the local oscillator signal are compared to the reference frequency signal to generate a duration that is a deviation between the desired frequency and the desired frequency. This error pulse is lowpass filtered to generate the tuning voltage of the local oscillator. Since the control unit 21 mainly uses digital components, the lowpass filter required for the phase locked loop is preferably located in the tuner 1.

The receiver control unit 29 is divided into deflection, video and audio control sections 29a, 29b and 29c for generating control signals for the deflection, video and audio signal processing units 11, 7 and 15, respectively. The deflection, video and audio control units 29a, 29b and 29c are connected to the respective control buses 39, 41 and 43 and the terminals of the control unit 21 (typically denoted by squares 45, 47 and 49). By means of the deflection, video and audio processing units 11, 7 and 15.

By way of examples of the various functions controlled by the receiver control unit 29, the deflection control unit 29a is configured to allow the deflection processing unit 11 to supply or not operate an operating voltage for various parts of the receiver. And "receive off" control signals. For this purpose, the deflection control unit 29a sets and resets in response to the user initial command from the user input 23 and is coupled to the control unit 21 via the microprocessor 25 and the data bus 31. It can include a flip-flop.

The video control unit 29b generates a control signal for controlling the brightness and contrast generated by the picture tube 9. For this purpose, the video control unit 29b may include a digital-to-analog converter (DAC) for generating a control voltage for the brightness and contrast function in response to the user initial command signal. Since the control unit 29 mainly contains digital components, the filter for the DAC is preferably included in the video processing unit 7. The BIO control unit 29c may also supply a character representative control signal to the video processing unit 7 for displaying an alphanumeric or other graphical element, for example the time of the selected channel number and / or date. Can be. For this purpose, the video processing unit 29 is October 5, 1976. W. It may include a character generator of the type described in US Pat. No. 3,984,828 issued to Bayer. As another example, the video controller 29b may be red, green and blue generated in response to red, green and blue signals supplied by an external source such as a home computer or video game, or a video signal supplied by the detector 5. It is possible to generate a control signal for controlling the switching unit in the video processing unit 7 for selecting one of the blue signals.

The audio controller 29c may include a DAC for controlling the volume level. It may also generate a control signal for selecting monophonic or stereophonic reproduction.

Jay on February 3, 1981. Jay Wolfford and Jay. ratio. In the name of George, U.S. Patent 4,249,089 discloses a device of an integrated circuit with facilities including a flip-flop and a DAC for controlling the on / off state and volume level of a television receiver, respectively. Similar DAC devices can be used to control brightness and contrast.

The CT-131 chassis television receiver, manufactured in RCA Corporation, Indianapolis, Indiana, and described in the 1984 CTC-131 Second Edition, submitted by RCA Color TV Basic Service Data, offers similar and additional control functions. Providing.

The various information signal voltages processed by the tuner (1), IF unit (3), detector (5), video processing unit (7), deflection processing unit (11) and audio processing unit (15) (user input unit (23). And the control and signal voltages generated by the control unit 21, as well as the command and data signal voltages processed by the microprocessor 25, may be applied to a common reference potential, e.g., to ground shown in FIG. Is standard. The ground reference potential is for example a series of conductors connected between the information signal processing units 1, 3, 5, 7, 11, 15 and the various reference potential input points of the control related units (21, 23 and 25). It is divided by the ground reference potential bus 51 provided.

If the bus 51 assumes a moment formed by a continuous, closed loop of critical regions (along with the separate ground reference potential input terminals 53a and 53b as a single terminal, to be discussed below), the ground bus 51 Will make it possible to conduct potentially large currents induced in itself due to the magnetic field generated by the deflection processing unit 11 and the associated deflection coil 13. Since the ground bus 51 is typically long, it exhibits a relatively large impedance between the reference potential input points of the unit to which it is connected. As a result, magnetically induced currents can cause relatively large and varying voltage drops to develop between reference potential input points that can adversely affect the operation of the television receiver. For example, such ground drops in grounding systems are found to produce noise and pulsations in the reproduced picture and audio responses. Therefore, it is desirable to avoid the use of a continuous, closed loop reference potential of any few areas.

One solution is that the control unit 21 is connected to ground with only one conductor rather than the control unit 21 connected to ground on both sides of the bus segments 51a and 51b in the manner shown in FIG. To avoid the formation of a continuous, closed loop ground path. However, this is that certain control units are particularly susceptible to ground disturbances that make loop construction of the ground bus 51 unavoidable. For example, a tuning error control pulse generated by a phase locked loop that may be included in the tuner control unit 27 and a text signal generated by a character generator that may be included in the video control unit 29b of the receiver control unit 29. Has been found to be particularly susceptible to ground potential disturbances. Although there is no continuous, closed loop ground path, ground disturbances can occur in normal operation due to the flow of return current from the processing unit and radiation. Therefore, it is preferable to connect the ground terminal of the control unit 21 to the tuner 1 and the video processing unit 7 by the bus segments 51a and 51b to reduce the ground disturbance caused by the normal return current (the Due to continuous, closed ground loops).

In the present grounding device shown in FIG. 1, the continuous closed ground of another method formed by the grounding bus 51 is broken up by dividing the control unit 21 into the first and second control units 27 and 29, Rather than a single reference potential input terminal for all control units 21, separate reference potential unit terminals 53a and 53b for each of the first and second control units 27 and 29 are provided. The reference potential input terminal 53b is connected to the reference potential input of the tuner 1 via the bus segment 51a, and the reference potential input terminal 53b is the reference of the video processing unit 7 through the bus segment 51b. Connected to the potential input. Since the reference potential input terminals 53a and 53b are not connected, a continuous closed ground loop that is susceptible to conduction of current induced from the magnetic field is not formed.

While the reference potential terminals 53a and 53b are not directly connected to each other, the threshold response gating circuit 55 is coupled between the terminals so that the terminals selectively connect to each other for conduction, whereby the voltage between the terminals exceeds a predetermined threshold. When clamping the voltage from one side to the other. The gating or clamping circuit 55 aims to prevent voltages exceeding the safety limit between the potential input terminals 53a and 53b. Without the gating circuit 55, the current draws the ground bus 51 due to a high energy discharge to ground relative to the image tube 9 where an excessively large voltage can be generated between the terminals 53a and 53b. Soar through. Since the semiconductor circuits of the tuner control unit 27 and the receiver control unit 29 are interconnected by the conductors of the data bus 31, the excessively large voltages generated between the terminals may cause various problems within the units 27 and 29. It can be coupled across semiconductor circuits and thereby damaged. This is suppressed by the gating circuit 55. Bi-directional gating circuits are used because the discharge cannot be predicted and therefore the polarity of the excess voltage cannot be predicted.

As shown in FIG. 1, the gating circuit 55 includes diodes 57a and 57b connected in parallel between the terminals 53a and 53b and of opposite polarity. In this case, the threshold and clamping voltage are the same in both directions (the direction of conduction), ie about 0.7 volts. It will be appreciated that the diodes 57a and 57b may be configured as base-emitter junctions of bipolar transistors having respective collector and base electrodes connected to each other.

Other gating circuit configurations are possible. As an example shown in FIG. 1 (a), a zener diode 59 may be used. In this case, the threshold and clamping voltage in one direction (the direction of conduction) are different from the other direction. If the voltage at the terminal 53a exceeds the voltage at the terminal 53b, the threshold and clamping voltage become the reverse conduction voltage of the zener or zener diode 59, and the voltage at the terminal 53b is the terminal 53a. If the voltage at is exceeded, the threshold and clamping voltage is about 0.7 volts of the net conduction voltage of the zener diode 59. Preferably, the zener voltage is chosen to be about 1.2 volts, preferably close to the forward voltage. Zener diodes eliminate the need for two inventive devices but are too expensive in nature. Zener diodes also tend to operate slower than normal diodes.

Although this special gating circuit is used, the threshold voltage is the highest expected potential between the terminals 53a and 53b due to the normal operation of the television receiver to ensure that the terminals 53a and 53b are not normally electrically connected for current between the terminals. (Ie gate 55 is not normally conductive).

In order to prevent interference between the control units 27 and 29 through the power path, the control unit 21 is provided with separate power supply terminals 61a and 61b for the control units 27 and 29, respectively. Terminals 61a and 61b are preferably bypassed to ground by respective bypass capacitors (not shown) to prevent radiation from the control unit. If desired, a filter, such as a series L-C filter, may be connected between the power supply terminals 61a and 61b to enhance insulation between the control units 27 and 29.

While the invention has been described in terms of particular embodiments, the following claims are intended to compensate for the modifications. For example, gating circuits with other thresholds and clamping voltages may be used.

Claims (8)

A reference potential bus 51 for dispersing a reference potential, first processing means 1 for processing a first voltage with respect to the reference potential under control of a first control voltage, and under control of a second control voltage Second processing means (7) for processing a second voltage with respect to a reference potential, first control means (27) for generating said first control voltage with respect to said reference potential, and said first with respect to said reference potential; Said first processing means having second control means 29 coupled to said first control means for generating a second control voltage and respective reference potential inputs connected to respective connection points along said reference potential bus, said A grounding apparatus for a display apparatus comprising a second processing means, the first control means and the second control means, wherein each of the connection points is normally electrically connected for non-conductivity between each connection point. The first and second control means 27 and 29 for selectively electrically connecting each connection point for conduction between each connection point when the voltage between each connection point exceeds a predetermined maximum. A grounding device for a display device, characterized by bi-directional gating means (55) connected between a reference potential input (53a, 53b). A grounding device according to claim 1, wherein said first and second control means are contained in the same integrated circuit. 2. The display device according to claim 1, wherein the gating means comprises first and second semiconductor junctions coupled in parallel between the reference potential inputs of the first and second control means and of opposite polarity. Grounding device. 4. A grounding device as claimed in claim 3, wherein the first and second semiconductor junctions comprise semiconductor junctions of respective first and second diodes (57a, 57b). A grounding device according to claim 1, wherein the clamping means comprises a zener diode (59). The grounding device of claim 1, wherein the reference potential is a single ground. 4. The apparatus of claim 3, wherein said first processing means comprises tuner means (1) for tuning various RF television signals comprising video and audio information corresponding to respective channels in response to a tuning control signal, wherein said first processing means comprises: 2 processing means is coupled to the tuner means, and video for processing video and audio signals representative of respective video and audio information corresponding to channels tuned by the tuner means in response to respective video and audio control signals. And audio processing means (7), wherein the first control means (27) generates the tuning control signal, and the second control signal (29) generates the video and audio control signals. Grounding device for display device. 8. A grounding device as claimed in claim 7, wherein said first control means comprises at least a phase locked loop and said second control means comprises a character generator.

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